Manufacture of vat dyestuffs



Patented Apr. 26,1927.

UNITED STATES PATENT OFFICE;

MAXIMILIAN PAUL SCHMIDT, OF BIEBRICHi-ON-THE-RHINE, GERMANY, ASSIGNOR, IBY MESNE ASSIGNMENTS, TO GRASSELLI DYES'IUFF CORPORATION, OF NEW YORK,

N. Y., A CORPORATION OF DELAWARE.

' MANUFACTURE OF VAT DYESTUFFS.

No Drawing. Application filed November 20, 1923, Serial No. 675,932, and in Germany November 25, 1922.

I have found that a very valuable vatdyestufl is obtained by melting the imideof the methoxynaphthalene-dicarboxylic acid with caustic alkali. The coloring matter formed dyes the fibre a very valuable marine-blue of excellent fastness to chlorine.

The process may be carried out as fol-.

'- potash at a temperature of 180190 centigrade while stirring and fu'sed at this temperature for some time. After cooling the bluish-black melt is dissolved in water'and oxidized, with air or another 'oxidizin agent. The separated dye-stufi' is filtere \Vith an alkaline hydrosulfite it yields a blue vat, from which cotton and wool are dyed in blue tints.

Emample l1. parts of the imide of methoxynaphthalene-1.8-dicarboxylic acid are mixed with 500 parts of powdered potassium hydroxide and 500 parts of tetraline and heated to about 17018() centigrade 'while stirring, until the formation of the dyestutl is finished. The mass is then cooled and separated from the main quantity of the tetraline.

Afterwards Water is added and the last part of the tetraline removed. Air is blown into the mass and finally the colorin matter drained off. From the alkaline filtrate further quantities of Vat-dyestufi may be precipitated by treating cautiously with salt.

The dyestufi' has the same properties as that described in Example 1.

Instead of caustic potash also caustic soda, sodiumamide or mixtures of these bodies may be employed, which is of advantage in suitable cases. The fusing may be effected with or without the addition of dimethoxyperylenetetracarboxylic acid, liar-- ing probably the. formula -"ocn= con.

1. Process of producing vat coloring matters consisting in "meltl'n the imide of methoxy-naphthalene-1.8-d1carb0xy1ic acid with alkaline agents.

2. As a new product the vat dyestuff substantially" identical with the product obtained by an alkaline fusion of the methoxynaphthalene 1.8-dicarboxylic-acid-di-imide, which most probably is a mixture of isomeric dimethoxy perylene-tetracarboxylic-acid-diimides, which is a black powder with a metallic luster'forming with an alkaline hydrosulphite solution a blue vat, from which cotton and wool are dyed blue shades.

3. As a new product the diimide of dimethoxyperylenetetracarboxylic acid having most probably the formula:

OCH; OCH;

MAXIMILIAN PAUL SCHMIDT. 

